Signaling system



H. E. HERSHEY SIGNALING SYSTEM 25, 1933 5 Sheets-Sheet l Filed Dec.

mm) DIG/7 RIFG/STERS INVENTOR- HARRY E. HERSHEY W? A TTY" 5 Sheets-Sheet 2 Filed Dec.

Oct. 6, 1936.

ATTY:

H. E. HER'SHEY 2,056,722

SIGNALING SYSTEM Oct 6, 1936.

Filed Dec. 23, 1953 5 Sheets-Sheet 4 0. 5, (PART 2) HARRY E HERsHEY H. E. HERSHEY SIGNALING SYSTEM 25, 1955 5 Sheets-Sheet 5 Filed Dec.

Patented Oct. 6, 1936 UNITED caries SIGNALING SYSTEM Application December 23, 1933, Serial No. 703,828

6 Claims.

The present invention relates in general to signaling systems, but is particularly concerned with the improvement of selecting systems used. in such systems.

The improvement, in the main, has to do with the provision of a combination of circuits and apparatus arranged to enable a speed of selection not possible to attain with switches directively and selectively controlled, as is the usual practice, and with economy in equipment not possible to attain in an all-relay selecting system.

In the present system a combination of switches assisted by relay groups, accomplish group and sub-group selection and final connection by operating as finders, thereby enabling them to 0perate at a speed limited only by their design and. adjustment.

The selective operations are further accelerated by providing digit registers, controlled by a key sender, to register all the digits required forthe selective operation as fast as the keys can be operated; and by providing circuit arrangements enabling the finders to start their hunting operation immediately following registration.

Other features of the invention have to do with the employment of circuits enabling the key sender to, after selection has been made, readily control the operation of the selected apparatus at the highest possible speed at which such apparatus will reliably operate, so that the over-all elapsed time between the initiation of selection and final operation is reduced to a minimum.

The accompanying drawings, comprising Figs. 1 to 4, inclusive, diagrammatically illustrate the circuits and apparatus employed, as an example, in attaining the foregoing features while Fig. is a schematic diagram illustrating the bank multiple connections.

The drawings, when arranged with Fig. 2-to the right of Fig. 1 and with Figs. 3 and 4 below Figs. 1 and 2, respectively, diagrammatically show a six-digit selecting system employed to select eight-position indicators, together with the neces sary circuits and apparatus for controlling such indicators once they have been selected.

Fig. 1 shows a key sender KS comprising ten key sets designated 1-0, respectively; a set of four switch control keys designated R, SR, GR, and SA, respectively; three indicating lamps comprising a sending pilot lamp SPL, a busy lamp BL, and an operate pilot lamp OPL; and two groups of relays each comprising a digit register and being labeled DR! and DB2, respectively, they being two of six such registers, as indicated.

In Fig. 2 and in the upper half of Fig. 4 are shown three switches designated DFI, DFZ, and DF3, termed digit finders. These finders are, mechanically, of the well-known type of Strowger vertical and rotary step-by-step switch in which the wipers are first operated vertically and are then rotated over their associated banks of contacts. Since these switches are herein employed as finders they are each provided with a vertical bank of contacts and an associated wiper. The relays associated with these switches and having the upper end of their cores shown shaded, are slow to energize, while those shown with their lower end shaded are of the slow to release type. At the'extreme right of these finders are shown two of two groups of co-ordinate relays associated with the bank contacts of the digit finders in such a manner as to make possible one million selections.

In Fig. 3, and in the lower portion of Fig. 4, are shown relay assemblies designated OS (part 1) and OS (part 2) which taken together constitute an operate sender. The function of this equipment is, as the name indicates, the sending of impulses as required to operate the selected indicators. The equipment OS (part 1) is the digit register of the sender, while OS (part 2) comprises the counting relay chain and other control relays of the sender.

Fig. 5 is a schematic layout showing the multiple connections of the lower banks. of the digit finders DFI, etc., to two attendants positions, it being understood that there may be as many attendants as desired each with a complete set of equipment suchas shown in Figs. 1 to 4, inclusive. In Fig. 5 reference characters corresponding to those of like equipment in Figs. 1 to 4 have been used. In order to aid in understanding the use to which the present system may be put reference may be had to U. S. Patent No. 1,960,781, granted May 29, 1934.

In brief, the selecting operations are performed as follows: the attendant, after determining the number of the indicator desired, quickly depresses such number on the non-locking keys of the sender KS. The digit registers DRI and DB2, and DB3 to DB6 (not shown) immediately operate to mark the banks of the digit finders DFI, DF2, and DF3, and these switches immediately start hunting for their vertically marked bank contacts and then for the contacts marked in their rotary'banks. The operation of the digit finder DFZ is in no way dependent upon the status of operation of DFl, nor is the operation of DF3 in any way influenced by either of the digit finders DFI or DFZ, and consequently if the operation of the keys of the key sender has taken place at great enough rapidity, all three of the digit finders may be operating simultaneously. The positioning of the three digit finders results in the selection of the co-ordinate relays and of circuits controlled by such relays in accordance with the digits set up on the key sender, resulting in the selection of the proper indicator. After selection has been made the attendant merely operates a key of the key sender momentarily, whereupon the digit register portion OS (part 1) of the operate sender functions to start its sender portion OS (part 2) to transmit the required number of pulses to the indicator at the highest possible speed at which such indicator will operate.

The system contemplates the possible use of a single selecting equipment alternately by several attendants each provided with a key sender such as KS and with supervisory lights in multiple with those shown. The sender pilot lamp SPL, for example, becomes lighted when any digit finder moves off normal to advise the various attendants of the busy condition of the equipment. The operate pilot lamp OPL lights up as soon as an operate impulse series in initiated by the attendant, assuming, of course, that the selecting operations have been completed by the digit finders.

The switch advance springs SA, when operated following the selection of an indicator, advance the digit finder DF3 one step into connection with another indicator, the position of which the attendant may also desire to change, and can then do so by simply operating the appropriate key of the sender instead of having to release the entire connection and make a new selection.

In the illustrated circuit arrangement the digit finder DFI has access to groups of station selecting relays; the digit finder DF2, to groups of contact springs of the station relays included in circuits extending to group relays; while the digit finder DF3 has access via contacts of these group relays to the indicators. Accordingly, if indicators in a group already selected are desired, the attendant may release the digit finder DF3 by operating the switch release key SR and can then, by operating the appropriate keys in the key sender, reoperate the digit finder DF3 to complete the new selection. In case the new selection necessitates reoperation of the digit finder DFZ also, the attendant, instead of operating the switch release key SR, operates the group release key GR and sets up the four instead of the two final digits on the key sender to make the required selection.

In case the attendant desires to select an indicator of another station he must release the entire equipment and reoperate the key sender accordingly. The release is accomplished by operation of the release key R.

A brief description of the equipment and the manner of its operation having been given, a more detailed explanation of the circuits and apparatus will now be gone into. In this connection it will be assumed that indicator I069 of station No. is the one desired. The attendant, accordingly, consecutively operates the spring combinations 8--0-1069 of the key sender. The momentary closure of the No. 8 spring combination causes a ground impulse to be transmitted over conductor IOI, the upper contacts of the combination, conductor I02, through break contacts of transfer relay I00, conductor I03, and through the winding of marking relay H5 to battery; and through the lower contacts of the spring combination to conductor I04, through contacts of relay I00, conductor I05, and through the winding of marking relay IIO to battery. These relays accordingly operate and, through the medium of their upper contacts, become locked up over a circuit including the winding of relay I00, which becomes efiective to operate relay I00 the instant ground potential is removed from the conductors I03 and I05 consequent to the release of the first operated spring combination of the key sender. This locking and operating circuit extends from battery through the windings and upper contacts of relays H0 and H5 in multiple, conductor I06, the winding of transfer relay I00, conductor I01, and conductor 208 to ground through break contacts of relay 235. It will be noted that the conductor I0'I normally feeds ground through break contacts of the marking relays H0, H5, I20, I30 and M0 to normally maintain the entire ten vertical bank contacts of the digit finder DFI grounded and that marking is accomplished by removing ground potential from the contact representing the level to which the digit finder is to be moved. In the present example it will be noted that the No. 8 conductor extending from the spring combinations of the marking relay group is the only one which is solely grounded by springs of marking relays II 0 and H5 and that, owing to the operation of these two relays, ground is removed from conductor 8 by the breaking of their contacts II I and H2. The switch DFI is therefore marked to move to the eighth level only.

The transfer relay I00, upon operating, at its upper contacts disconnects the key sender from association with the digit register DRI and associates it with the digit register DB2, the relays H5 and I40 of which operate consequent to .the depression of springs 0 of the key sender to remove ground potential from the tenth vertical row of rotary bank contacts of the marker bank. The transfer relay I00 also, at its lower contacts, extends ground from conductor I 07 to conductor I09 and through the winding of slowto-pull-up relay 200 and through the break contacts of this relay and winding of interrupter relay 205 in multiple to battery. The relay 205 operates before the relay 200 and at its upper make contacts completes a locking circuit for itself independent of the break contacts of relay 200. This locking circuit extends from the grounded conductor 208, through the upper make contacts of relay 205, the interrupter contacts of vertical magnet 2 I 5, conductor 22 I, and the winding of relay 205 to battery. It will be observed that a branch of this circuit also extends through the upper winding of series relay 2I0 to battery and that, upon operation of relay 200, ground on conductor I09 is extended through the lower make contacts of relay 205 to and through the lower winding of slow release series relay 2I0 to battery, so that this relay is also energized via its lower winding at this time.

It will be observed that ground potential supplied to the lower winding of relay 2I0 also extends to the winding of the vertical magnet 2I5 and. battery. The slow-release relay 2I0, upon operating, at its contacts 222 opens a point in the initial operating circuit of the rotary magnet 230 to prevent its operation prior to the completion of selection under control of the vertical wiper 258, at its contacts 224 opens a point in the operating circuit of operate sender start relay 300, and at its contacts 223 applies ground potential countered by the vertical wiper 258.

via the interrupter contacts of rotary magnet 232 to the upper winding of series relay 225 and to the winding of interrupter relay 220 in multiple to battery. The relay 220, upon operating, at its inner lower contacts closes a point in the operating circuit of the rotary magnet 232 and at its lowermost contacts closes a shunt circuit around the contacts 223 of relay 210 so as to prevent the interruption of the circuit of relays 220 and 225 upon the restoration of series relay 2|0, which subsequently occurs at the termination of the vertical operation of the switch.

The vertical magnet 2i 5, upon operating, at its interrupter contacts breaks the traced locking circuit of interrupter relay 205, causing that relay to restore to normal, while the mechanism driven by the vertical magnet 2l5 permits the closure of off normal contacts 250 and 25! and elevates wipers 258, 260, 26I and 262 one step with the wipers 258 in engagement with its first contact. In the selection under consideration this contact and all others, excluding the eighth level contact, have ground potential thereon; accordingly, this ground potential passes back over conductor 259, through the interrupter contacts of rotary magnet 2 l5, and through the upper winding of slow-release relay M and the winding of interrupter relay 205 in multiple to battery. The relay 205 accordingly energizes to again connect ground potential to the winding of the vertical magnet 2 l5, which operates to elevate the wipers of the switch a second step. This interaction of the stepping relay 205 and the vertical magnet 2|5 continues so long as ground potential is en- When the ungrounded contact, the eighth in this instance, is encountered, the interrupter relay 205 remains deenergized; and since the slow-release relay 2 l0 no longer receives pulses of current, it also restores to its normal position. The reclosure of contacts 224 is without effect at this time owing to the energized condition of relay 225, while the contacts 223 opening are without effect owing to the substitute circuit closed through contacts of the energized relay 220. The relay 2"], however,

at its contacts 222 now completes an initial operating circuit to the rotary magnet 232 and a circuit through the lower winding of series relay 225 in multiple by connecting them to the conductor I23, which was grounded through the lower contacts of transfer relay I00 upon the latter relays operation consequent to the operation and restoration of the key sender spring combination 0 in the course of setting up the second digit of the desired number.

The series relay 225, which, as previously explained, was operated in multiple with relay 220 and which also is maintained operated so long as pulses are being transmitted to magnet 232, at its lower break contacts maintains a point in the operating circuit of relay 300 open during rotary selection, and at its outer upper break contacts removes ground from the conductor 248 so that the associated wiper 262 is disconnected from potential while passing over its bank contacts, and for like reason at its inner upper contacts it removes ground potential from conductor 249 with which is connected the wiper 28!, and connects the wiper 26! with the winding of relay 230 and battery for a purpose which will subsequently be made clear.

Returning now to the operation of the switch consequent to the energization of the rotary magnet 232, it will be observed that this magnet, at its interrupter springs breaks the operating circuit of interrupter relay 220 which, accordingly, restores, and at its inner make contacts interrupts the circuit of the rotary magnet 232 which, accordingly, becomes deenergized. The energization of the rotary magnet 232 has, however, resulted in the movement of wipers 260, 26!, and 262 into engagement with the first set of contacts in the eighth level of their banks. As previously explained and as clearly indicated, all of the bank contacts associated with wiper 260 are multipled vertically and normally have ground potential applied to them through contacts of the relays of the digit register DB2. In the present example, the 0 spring combination in the key sender has been operated, thus bringing about the operation of relays H5 and M0 of the digit register DB2, which as previously explained resulted in the removal of ground potential from the tenth or 0 vertical row of contacts in the rotary marker bank. The wiper 260, therefore, upon encountering the first grounded contact in the eighth level of the bank, places ground potential back over conductor 253, through the interrupter contacts of the rotary magnet 232, through the upper winding of slowrelease relay 225, and through the winding of interrupter relay 220 in multiple to battery. The relay 225 accordingly remains energized while the relay 220 again operates to again close the operating circuit of the rotary magnet 232. The interaction of relay 220 and of the rotary magnet is thus continued so long as grounded contacts are encountered or, in this instance, until the wiper 260 arrives into engagement with the tenth contact of the bank. When this occurs the interrupter relay 220 fails to again energize and accordingly rotary movement of the switch ceases. An instant later slow-release relay 225, no longer receiving ground pulses, also becomes deenergized.

The slow-release relay 225, upon restoring, at its lowermost contacts closes a point in the op erating circuit of relay 308 of the operate sender, at its inner upper break contacts connects ground to wiper 26! by way of conductor 249. This ground on wiper 26l now lights up the station lamp, but the application of ground to this wiper is also for another purpose which will subsequently be made clear; and at its outer upper break contacts completes a circuit for the No. 80 station relay R80. This circuit extends over conductor 248, wiper 252 now in engagement with the eightieth lower bank contact of the finder DFI, conductor 263, and the winding of relay R80 to battery. The relay R80, accordingly operates to connect the 100 lower terminals of the lower bank of the digit finder DF2 with the group of relays of station 80 which are arranged to close circuits or points in circuits extending to the magnets of the indicators of the No. 80 station.

The digit registers DR3 to DB6, inclusive, are identical with the digit registers DR! and DB2 and are in like manner controlled by the attendant to register or mark the banks of the digit finders DF2 and DF3. Likewise, the digit finders DF2 and DFE are operated in identically the same manner as is the digit finder Dl l. It will be appreciated, therefore, that the instant marking occurs or is accomplished in the banks of the digit finders DF2 and DFS they will immediately be operated accordingly.

In the present example the digit finder DF2 elevates its wipers one step and then rotates them into engagement with their tenth set of bank contacts. The wiper 212 of the digit finder DF2 accordingly closes a circuit to the No. 10 relay of one-hundred of such relays of station 80 made available to the digit finder DF2 by operation of the station relay R80. The relay RIO accordingly operates to close points in the operating circuits of a maximum of one-hundred indicators of station 80 made available to the switch DF3 through its contacts.

In the present example, the digit finder DF3 has its wipers positioned on their sixty-ninth contacts and the indicator 80!069 is accordingly made available for operation over the wiper 412 of the digit finder DPS. It will be noted that the digit finder DF3 instead of applying ground potential to the contacts selected, as did the digit finders DF! and DF2, connects this wiper to a conductor 40! extending to make contacts of pulsing relays of the operate sender OS (part 2) and that no operation of the selected indicator occurs consequent to the selection.

Indicator operation It will be assumed that the attendant desires to move the indicator 80!!)69 eight steps and accordingly momentarily operates the No. 8 spring combination of his key sender KS, thereby connecting ground potential out over the conductors I02 and I04 through operated contacts of the relay Hi0, conductors !36 and I26, through operated contacts of the transfer relay I00, to conductors I31 and !21, through the remainder of the chain circuit including contacts of the transfer relays of the digit registers DB3 to DB6 (not shown), conductors I38 and !28, through the windings of marking relays 3!5 and 328, respectively to battery. Upon the restoration of the No. 8 spring combination by the attendant these relays become locked up over a circuit including their upper contacts and the relay 305, the latter relay being connected to ground via conductor 308 and the lower contacts of relay 468. The relay 395, upon operating, at its contacts closes a point in the operating circuit of relay 300 which is completed the instant that all digit finders have completed their selecting operation. This circuit extends from ground potential applied through the lower break contacts of series relay 425, the lower break contacts of series relay 4!0, conductor 228, the lower break contacts of series relay 225' and 210, respectively, conductor 221, the lower break contacts of series relays 225 and 2!0, respectively, conductor 226, the contacts of relay 305, and the winding of relay 300 to negative battery. The relay 300 accordingly becomes energized and at its contacts applies ground potential to the conductor 23!. One branch of this conductor extends to the operate pilot lamp OPL and battery, while the other branch extends to the lower winding of relay 455 and to the winding of counting relay 46! in multiple to battery. The lighting of the lamp OPL, as previously stated, serves to advise the attendant that operate impulses are being transmitted. The relay 455, upon operating, at its inner upper contacts completes a looking circuit for itself in multiple with the relay 400 of the digit finder DF3 and at its upper contacts opens a point in the normally employed control circuit of the digit finder DF3 for a purpose which Will be hereinafter explained.

The relays 3!5 and 320, upon operating, at their contacts 3!1 and 32! connect the conductor 1, extending to the upper armature spring of counting relay 462, with the conductor 304 and the winding of pulsing relay 410 to negative battery, and at contacts 3!6 and 322 connect the conductor 8, extending to the upper armature spring of counting relay 46!, with the conductor 306 which extends to the pulsing relay 460 and battery.

The ground potential applied to the winding of relay 46!, it will be noted, also extends via the upper break contacts of this relay to conductor 8 and over the previously traced circuit to the pulsing relay 460 and negative battery. The relay 460, upon operating, at its contacts 480 transmits an operating pulse out over conductor 40!, via the break contacts of relay 435 to the operating magnet of the indicator; at its contacts 48! it opens a point'in the operating circuit of the next counting relay of the chain, and at its contacts 482 becomes locked up to conductor 23!, via contacts 483 of slow-to-pull relay 499, hold conductor 415, and the inner upper make contacts of relay 46!. The relay 46!, upon operating, in addition to closing the circuit just traced; at its inner upper break contacts opens the initial operating circuit of relay 460, at its upper outer contacts transfers the conductor 8 and the connected pulsing relay 460 into connection with conductor 6 of the group, and at its lower contacts closes a point in the operating circuit of counting relay 462.

The slow-to-pull relay 499, which is energized in multiple with the indicator magnet, is made just slow enough to operate to insure the proper operation of the indicator. This relay, upon operating, it its contacts 484 opens the looking circuit of the operated pulsing relay, in this instance 460; and at its contacts 484 opens a second point in the operating circuit of the next counting relay of the chain, in this instance, 462. The relay 460, upon restoring, at contacts 480 opens the circuit of relay 499 and of the indicator magnet; and at its contacts 48! closes a point in the operating circuit of counting relay 462. The relay 499 restores an instant later and at its contacts 484 completes this circuit, which extends from the ground on conductor 415, through contacts 484, 48!, the lower make contacts of relay 46! and the inner break contacts of 462 to battery. A branch of this circuit also extends via the outer upper break contacts of relay 462 to the conductor 1 and over a previously traced circuit to the pulsing relay 410 and battery. This latter relay therefore energizes and at its contacts 485 transmits a second pulse out over the previously traced circuit to relay 499 and to the magnet of the indicator. The relay 462 at its lower contacts prepares an operating circuit for relay 463, at its upper inner make contacts locks itself up to the conductor 415, and at its upper outer contacts connects the conductor 1 with conductor 5. The pulsing relay 410 and the slow-topull relay 499 cooperate in the same manner as did relays 460 and 499, the latter relay upon deenergization completing the operating circuit of counting relay 463. The relay 462 at its lower contacts applies ground potential via the upper break contacts of relay 463 and the upper make contacts of relay 46! to the conductor 8, thereby bringing about the operation of relay 460 a sec- 0nd time, resulting in a third impulse being transmitted to the indicator magnet. This operation of the subsequent relays 463 through 468, it will be readily seen from the foregoing, effects the alternate energization of pulsing relays 460 and 410; and when ground potential is applied to the winding of relay 468 the final or eighth impulse will be transmitted via the upper break contacts of this relay, the upper make contacts of relay 4%, the upper make contacts of relay 464, and the upper make contacts of relay 462, to conductor 1, resulting in the operation of pulsing relay 479.

Upon the operation of relay 468 ground potential is removed from conductor 398, resulting in the deenergization of relay 395 and the marking relays 315 and 329. An instant later the slow-release relay 399 becomes deenergized and at its contacts removes ground potential from conductor 23!, thereby extinguishing the operate pilot lamp OPL and unlocking the counting relays 46I to 468, inclusive. They accordingly become deenergized.

Should the attendant have desired only to operate the indicator five steps instead of eight, he would have actuated the spring combination of the key sender, resulting in the energization of appropriate ones of the marking relays to render eifective pulses transmitted through only the latter five of the counting relays instead of all eight of them.

The operate sender pulsing relays have been shown with locking circuits controlled by relay 499. This relay and these circuits are not absolutely necessary to the successful operation of the indicators under control of the pulsing relays. The addition of this equipment, however, renders the adjustment and control of the circuits less critical and is therefore thought to be desirable.

Multiple operation- In the foregoing detailed description no consideration was given to the fact that the indicators might be made selectable to other attendants provided with selecting and control equipment in duplicate of that shown in the drawings of the instant application.

In multiple operation the upper bank contacts of the lower banks of digit finders DFI, DF2, and DF3 are multipled with the corresponding bank contacts of the corresponding digit finders of the system, irrespective of the number of attendants positions which are provided, and the lower bank contacts of the lower banks are also connected in multiple with the corresponding bank contacts of the digit finders of other attendants as indicated in Fig. 5.

It will be assumed that the attendant operates the key sender KS to make the selection of an indicator 89I969 at a time that this indicator is already in a selected state. In such case when the digit finder DFI completes its selective op eration, and prior to the restoration of slow-release relay 225, will find ground potential on the bank contact encountered by wiper 26!. This results in the operation of guard relay 239. This relay becomes locked up through its own upper contacts from ground on conductor 241 upon restoration of slow-release relay 225, and at its lower contacts supplies ground potential to conductor 229. Under the present assumption, that the indicator 895989 has already been selected by another attendant, the guard relay 239 of the digit finder DF2 and the guard relay 439 of the digit finder DF3 are each operated and ground potential is accordingly extended via conductor 229, the lower contacts of relay 239', conductor 429, the lower contacts of relay 430, and conductor 43! to the winding of relay 435 and negative battery. The relay 435, upon operating, at its upper contacts opens the control circuit extending over conductor 49! to the magnet of the indicator 89l969 so that the attendant cannot exercise any control over this indicator while it is connected with over another switch train, and at its lower contact applies ground to conductor 232 extending to the busy lamp BL which lights up to advise the attendant that the indicator has already been selected by another attendant and that it will be useless for him to attempt to operate the selected indicator under these circumstances.

In order to illustrate the utility of the switch advance springs SA, it will be assumed that the attendant not being able to operate the selected indicator 89|969 decides to operate the indicator 89l969. In such case, by operating the switch advance springs SA, a ground impulse is transmitted therefrom over conductor 233 direct to the rotary magnet 432 of the digit finder DF3 which accordingly advances its wipers into engagement with the next, and in this instance last, set of contacts 69' in the bank of the digit finder DF3 to which is connected the indicator 89I969.

In instances where the wipers of the switch have been initially positioned on their first bank contacts of a level the attendant may, obviously, by use of the springs SA, advance them into successive engagement with all of the indicators of such level without needing to release the switch. It will be recalled that the initial operating circuit to the counting relay chain of the operate sender also effected the energization of relay 455 and that this relay became locked up in multiple with the relay 499 of the digit finder DF3. This relay at its break contacts disconnects the wiper 469 from connection with stepping and series relays 420 and 425 so that pulses will not be transmitted to them as the wiper 469 is advanced over grounded contacts under control of the springs SA.

Release It will now be assumed that the attendant, having selected an indicator, and having operated it if he so desired, decides, as no further selections are required for the time being, to release the operated equipment. He accordingly momentarily operates the release springs R, thereby transmitting a ground impulse from these springs, over the conductor 393 to the release control relay 459 and negative battery. The relay 459, upon operating, at its upper contacts applies ground potential to conductor 238 extending directly to the release control relay 235 of the digit finder DFI and battery. This relay, accordingly, becomes operated, and is locked energized over a circuit including its inner lower contacts and the off-normal springs 259; at its upper contacts it breaks the circuit of the station relay R89, permitting that relay to become deenergized; at its upper make contacts it completes the obvious circuit for the release magnet 249 of the digit finder DFI which accordingly restores to its normal position; and at its lowermost contacts it removes ground potential from the conductor 298. The removal of ground potential from conductor 298 results in the deenergization of the transfer relay I99 and the operated marker relays of the digit register DRZ, in the removal of ground potential from the associated conductor I91 which has up to this time maintained the transfer relay I99, marker relays, and the slowto-pull relay 299 of the digit finder DFI energized. All of these relays accordingly restore to their normal position in readiness for reoperation by the key sender.

It will be recalled that the ground potential supplied to the contacts of the vertical and rotary marker banks of the finder DFI was also supplied thereto via the break contacts of relay 235. The off normal contacts 250 do not open the circuit of 235 until the switch is restored to normal and, therefore, this relay holds the ground potential off the marker bank contacts during this time to prevent possible false operations during retrograde movement of wipers 258 and 260 over their contacts. The relay 450, at its two other sets of contacts, complete similar release control circuits to the digit finders DFZ and DF3, which bring about the release of the digit finders DFZ and DF3 and their associated digit registers in the same manner as described in connection with the release of digit finder DFI and its associated registers. The removal of ground potential from the relay B of finder DF3 also effects the deenergization of relay 435 which accordingly also restores.

In certain instances the attendant may, after selecting an indicator, decide that he also desires to select an indicator of the same station but in some other group and sub-group. Under these circumstances, he may operate the group release springs GR to momentarily transmit ground potential out over the conductors 3M and 302. These conductors, it will be noted, connect with the conductors 238 and 438 extending to the release control relays 235' and 445 of the digit finders DFZ and DF3, respectively. Accordingly, only these two switches and their associated digit registers are released. The selection of the desired indicator of another group and sub-group may accordingly now be accomplished by merely setting up the last four digits of the desired indicator on the key sender.

Should the attendant desire to select some other indicator which has been made available to the digit finder DF3 as a result of the operated condition of relay RIO, he will simply operate the switch release spring combination SR momentarily, thereby transmitting ground from ths spring combination over the conductor 361, conductor 438, and to the winding of release magnet 446 of the digit finder DF3 to battery. The digit finder DF3 is accordingly restored to normal, enabling the attendant to reposition it into connection with another desired indicator by operating the key sender to transmit the two final digits representing the number of the indicator desired.

While the switches DFI, DFZ, and DF3 have been shown and described as having only marking banks and one selecting bank they eachmay, and ordinarily will, be equipped with an additional display control bank having connections to an associated panel of indicating lamps arranged at the attendants position, as shown in Figs. 1 and 2 of the copending Hershey application, Ser. No. 502,111, filed December 13, 1930. This additional equipment has been omitted from the instant disclosure for the sake of simplicity. The conductors with which the wipers having access to the display banks when such are provided, having access to the display banks when such are provided, have, however, been shown and labeled 262, 212', and 412, respectively.

Having described the invention what is considered to be new and is desired to be protected by Letters Patent will be set forth in the following claims.

What is claimed is:

1. In a signaling system, a two-motion finder switch equipped with two marker banks, and a bank through which circuit selections may be made, a pair of digit registers associated with said switch including relays, a set of circuit controlling keys, a relay having contacts normally maintaining one of said digit registers operatively associated with said key set, certain of the relays of said one digit register having operating circuits closed, by the operation of a key in said set, to effect marking of one contact of one of said marker banks; an operating circuit for said first relay made effective by the restoration of the operated key, contacts on said relay thereupon effective to associate said key set with the other digit register of the pair and for initiating the primary hunting operation of said switch, certain of the relays of said other digit register having operating circuits closed by the operation of a key of said set to effect marking of a contact in the other marking bank of said switch, a relay of said other digit register having an operating circuit made effective by the restoration of the last operated key of the set to initiate the secondary hunting operation of said switch, and means in said switch for delaying the secondary hunting operation in case said last relay is operated prior to the completion of the prim ary hunting operation.

2. In a selecting system, a plurality of operable elements, an attendants position, means including a plurality of finder switches, and associated relays and circuits controlled from said position, to accomplish selection for operation of any one of said elements, another attendants position, a second plurality of finder switches, means controlled from said other position to operate said last plurality of finder switches to select one of said elements; a chain guard circuit, including contacts of relays of each of the last employed plurality of finder switches, and means for completing said circuit consequent to a selection of an element already selected by the first group; a relay in said circuit operated upon its closure, signaling means actuated by said relay to notify the attendant of the prior selection of the element, and an attendants operating control circuit for the element rendered ineffective by said relay.

3. In a selecting system, a group of devices, a group of finder switches, circuits for said devices accessible to said switches, means for marking the banks of said finders in accordance with the device with which a connection is desired, means for starting the respective finders hunting for their marked contacts at substantially the same time such contacts are marked, a set of circuit controlling keys, a device operating sender, means for placing said sender under control of said key set immediately following the initiation of operation of the last one of said switches, and a circuit having contacts in each of said switches for preventing said device operating sender from performing its impulse transmitting functions until all of said switches have completed their selecting operations.

4. In a signaling system, an equipment selecting and operating system including a group of finder switches and a group of relays and circuits through the medium of which access to desired pieces of equipment is attained, a chain of sequentially actuated groups of digit register relays for marking such finders in accordance with the selection desired and for initiating their operation, relays and apparatus for transmitting operating influences to the selected equipment, another group of relays operated at the will of an attendant following the marking and initiating of all said finders to mark said apparatus for operation in accordance with the operation desired, and means for preventing said apparatus from functioning until all of said finders have completed their selecting operations.

5. In a selecting system, a plurality of attendants positions, a plurality of devices to be selected, a series of selecting switches having access thereto, a set of digit keys at each position, means responsive to successive operations of said keys by the attendant at one of said positions tocause the operation of a series of said switches to select a device, a sender, means responsive to the operation of the last switch of the series for connecting the key set to the sender and the sender to the device, and means responsive to a subsequent operation of the key set to control the sender to transmit impulses to the device through the last of said switches only.

6. In a selecting system, devices to be selected and controlled, a set of digit keys, a series of digit registers, a series of selecting switches, an impulse sender, means responsive to the successive operation of the keys of said set for successively marking the banks of said switches and starting them into operation to find the marked contacts in their banks to select a device, each switch started as soon as its bank is marked independent of the stage of operation of any other switch, means responsive to the completion of the selecting operation by all switches for connecting the key set to the sender, said sender responsive to the operation of a key of said set for transmitting impulses to the selected device.

HARRY E. HERSHEY. 

